This invention relates to curved escalators.
As disclosed in Japanese Patent Publication No. 48-25559, a curved escalator which has a circular shape in plan view is provided on a framework with an endless stairway path including an inclined load-bearing run on the upper side of the loop path, a return run on the lower side of the loop, and turn-around portions at the opposite ends of the runs, and a plurality of segment-shaped steps are arranged in the stairway path with their step axles connected to an inner and an outer step chain loop defining the stairway path. In the curved escalator, an inner and an outer sprocket wheel having different diameter are mounted in the upper and the lower turn-around portions to engage and guide the inner and the outer step chain loops, respectively. The inner and the outer sprocket wheels in either the upper or the lower turn-around portion are driven by a drive mechanism for turning around the inner step chain at a radius smaller than that of the outer step chain, whereby the step axles connected to the inner and the outer step chain loops and hence treads of the steps are moved along a conical surface in the turn-around portions.
However, with the conventional curved escalator as described above, since the bottom surfaces between the teeth of the sprocket wheel are formed with no slope with respect to the axis of the sprocket wheel, since the step axles engage selected teeth of the sprocket wheel at a predetermined pitch, and the step axles turn around along a conical surface with their axes inclined with respect to the axis of the sprocket wheel, it has been difficult to cause the steps to smoothly and reliably turn around and a problem arises that the step chain oscillates, providing an uncomfortable ride.